Appliances are well known for fitting a tire on a wheel and for removing a tire from a wheel, which comprise a horizontal rotatably mounted plate with clamps that can be moved towards the center of the plate in order to clamp the wheel, a vertical pillar on which is provided an arm with an oscillating motion in a horizontal plane above the aforesaid plate and in the aforesaid arm a bar, the level of which is adjustable, having at its lower end a small guiding wheel for separating the bead of the tire over the wheel rim, and also a small pressure wheel for driving the bead of the tire into the groove of the wheel rim, which pressure wheel is located along the circumference of the wheel.
In a known appliance there is provided on the vertical pillar a bracket in which is being screwed an adjusting screw with a small handwheel; the free end of said screw presses against the pivoting arm. After the arm has been turned so that the side of the small pressure wheel contacts the wheel rim, the adjusting screw is being turned so that the arm, and thus the small pressure wheel, parts and is set at a small distance from the wheel rim, resulting in the small wheel not being able to rub against the rim and damage it when the plate rotates.
This adjusting screw, however, has a drawback in that it is necessary to have the small handwheel make several revolutions before the small pressure wheel reaches the desired position. Thus, adjustment of the small pressure wheel cannot be achieved rapidly.